The RG oilfield sonic acquires
full-waveform digital acoustic data using two piezoelectric transmitters and two receivers.
PRINCIPLE OF MEASUREMENT: A piezoelectric transmitter stimulated by a high-voltage pulse radiates a high-frequency acoustic wave through the borehole fluid and formation to the receiver array.
Compensated sonic mode:
The two transmitters are fired in rapid succession. The waveforms arriving at each of the two receivers are transmitted to surface in a digital format. The time of the first compressional arrival at each receiver is calculated by surface software. The data is depth-shifted and processed to remove the influence of the borehole fluid path, tool tilt and caving ('depth-derived borehole compensation' DDBC).
CBL mode: A single transmitter is fired and full-waveform data is acquired by each of the two receivers. The surface software records 3’ first arrival amplitude data and the 5’ full sonic wave-train (VDL). The attenuation of the first arrival is related to the bond quality and the strength of cement.
FEATURES
High-energy transmitters for maximum penetration
Fully digital telemetry
Δt measurements at multiple spacings
Depth-derived borehole compensation for borehole tilt and caving
Amplitude and waveform data in CBL mode with industry-standard 3’ and 5’ spacings
Oil-filled mandrel with pressure compensation
MEASUREMENTS
Formation velocity (slowness)
Compensated Δt from each receiver
Tx-Rx spacings: 3ft, 4ft, 5ft, 6ft
Cement Bond Log (CBL) amplitude and waveform
APPLICATIONS
Open Hole:
Lithology
Porosity
Rock strength and elasticity
Fracture indication
Time to depth correlation for seismic
Cased hole:
Location of poor or missing cement
behind casing
